I’m afraid that is not possible with X-Plane.
What I understand is there are only up to two versions of X-Plane that you can download: The latest Release, and a newer Beta, if available. Since 11.30 is considered a Release, that makes it the one and only at this time.
I always backup my entire X-Plane folder structure, less “Custom Scenery” (just too huge), before accepting any X-Plane update.